Re: [Devel] Compiler warning

[David Turner]

Hello Steve,

Steve Dias wrote:
> Hi,
>
> I get the following compiler warning with the Algorithmics MIPS GNU
> compiler, with '-Wall' and '-O3':
>
> *       util/freetype2/src/sfnt/ttcmap0.c: In function
>         `tt_face_build_cmaps':
> *       In file included from ./util/freetype2/src/sfnt/sfnt.c:24:
> *       util/freetype2/src/sfnt/ttcmap0.c:1702: warning: variable `p'
>         might be clobbered by `longjmp' or `vfork'
> *       util/freetype2/src/sfnt/ttcmap0.c:1735: warning: variable
>         `pclazz' might be clobbered by `longjmp' or `vfork'
>
> A google search showed that this may be a common warning from gcc given
> the combination above, and I even found a reference to a similar warning
> in earlier FreeType code, but in my relatively brief search, I couldn't
> find a reasonable solution.
>
> Given how warning-free the code is (Level 4 in DevStudio project!), I
> figure maybe it's my tools or other configuration, or there's a
> straightforward way to suppress this warning that's come up before.
>
> Any ideas?
Well, I only experience this warning with GCC and optimization on, and
I strongly suspect this to be a compiler bug, as spotted by Werner. Fact
is that the variables are declared "volatile" and should never get
clobbered by the 'longjmp' in any way.

Seems that the GCC optimizer does funny things to the code generated. I
don't have any idea regarding its impact on the compiled code robustness
though... :-(

Regards,

- David Turner
- The FreeType Project  (www.freetype.org)